1. Field of the Invention
The present invention relates to a pneumatic tool, and more particularly to a pneumatic tool with a lubricating oil reservoir.
2. Description of Related Art
A pneumatic tool like a pneumatic chisel in accordance with the prior art shown in FIG. 10 comprises a hollow housing (60) with an actuating mechanism (70) and a handle (62) extending from the hollow housing (60) to connect with a high-pressure air source with a high-pressure air connector (64). The actuating mechanism (70) includes a reciprocating valve (72) to control the direction of the air flow to propel an piston (76) to slide along a cylinder (74) forwards and backwards. Consequently, the high-pressure air can be directed into the hollow housing (60) through the high-pressure air connector (64) and the handle (62), and the actuating mechanism (70) will be actuated to impact a tool shank (78) for hammering or chiseling. In addition, a lubricating oil tank (80) is mounted on the high-pressure air connector (64) to provide lubrication for the actuating mechanism (70) when the pneumatic tool is operated.
However, because the conventional oil tank (80) is attached to the high-pressure air connector (64) and connects with the high-pressure air hose, the structure of the tank (80) is complex and the size of the pneumatic tool is large, which impacts both the manufacture and operation of the tool. In addition, at least one exhaust port (742) is formed in the cylinder (74) to release the air that propels the piston (76) along the cylinder (74) to overcome a high back pressure when the piston (76) moves in the opposite direction. However, all of the high-pressure air cannot be exhausted from the cylinder (74) in the conventional pneumatic tool. The air still remaining in the cylinder (74) will keep the piston (76) from returning to the initial point, thus shortening the stroke of the piston (76) and decreasing the power delivered to the tool shank.
To overcome the shortcomings, the present invention tends to provide an improved pneumatic tool to mitigate or obviate the aforementioned problems.